linux、windows断网判断机制

linux：

#include <linux/sockios.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/if.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define ETHTOOL_GLINK        0x0000000a /* Get link status (ethtool_value) */
typedef enum { IFSTATUS_UP, IFSTATUS_DOWN, IFSTATUS_ERR } interface_status_t;
typedef signed int u32;
/* for passing single values */
struct ethtool_value
{
    u32    cmd;
    u32    data;
};
interface_status_t interface_detect_beat_ethtool(int fd, char *iface)
{
    struct ifreq ifr;
    struct ethtool_value edata;
                                                            
    memset(&ifr, 0, sizeof(ifr));
    strncpy(ifr.ifr_name, iface, sizeof(ifr.ifr_name)-1);
    edata.cmd = ETHTOOL_GLINK;
    ifr.ifr_data = (caddr_t) &edata;
    if (ioctl(fd, SIOCETHTOOL, &ifr) == -1)
    {
 //       perror("ETHTOOL_GLINK failed ");
        return IFSTATUS_ERR;
    }
    return edata.data ? IFSTATUS_UP : IFSTATUS_DOWN;
}
int main (int argc, char *argv[])
{
    FILE *fp;
    interface_status_t status;
    char buf[512] = {'\0'};
    char hw_name[10] = {'\0'};
    char *token = NULL;
    /* 获取活动网卡名称 */
    int fd_eth;
    int interfaceNum = 0;
    struct ifreq buf_eth[16];
    struct ifconf ifc_eth;
    struct ifreq ifrcopy_eth;
    if ((fd_eth = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    {
        perror("socket");
        close(fd_eth);
        return -1;
    }
    ifc_eth.ifc_len = sizeof(buf_eth);
    ifc_eth.ifc_buf = (caddr_t)buf_eth;
    if (!ioctl(fd_eth, SIOCGIFCONF, (char *)&ifc_eth))
    {
        interfaceNum = ifc_eth.ifc_len / sizeof(struct ifreq);
 //       printf("interface num = %d\n", interfaceNum);
        while (interfaceNum-- > 0)
        {
            if(strstr(buf_eth[interfaceNum].ifr_name,"eth") != NULL)
            {
                printf("device name:@@@@@@@@@@@\n");
                printf("device name: %s\n", buf_eth[interfaceNum].ifr_name);
                strncpy(hw_name,buf_eth[interfaceNum].ifr_name, strlen(buf_eth[interfaceNum].ifr_name));
            }
        }
    }
//判断是否插入网线
    int fd;
                                                             
    if((fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        perror("socket ");
        exit(0);
    }
    me/yckj/Desktop/linux上svn的使用.docx'
    status = interface_detect_beat_ethtool(fd, hw_name);
    close(fd);
    switch (status)
    {
        case IFSTATUS_UP:
            printf("%s : link up\n", hw_name);
            break;
                                                                 
        case IFSTATUS_DOWN:
            printf("%s : link up\n", hw_name);
            break;
                                                                 
        default:
            printf("Detect Error\n");
            break;
    }
    return 0;
}

windows：

#include <stdio.h>
#include <Wininet.h>
int net_link_check()
{
    int ret;
    DWORD   flags;//上网方式
    BOOL   m_bOnline = TRUE;//是否在线
    m_bOnline=InternetGetConnectedState(&flags,0);
    if(m_bOnline)//在线
    {
        printf("在线\n");
        ret = 1;
    }
    else
    {
        printf("不在线\n");
        ret = 0;
    }
    return ret;
}

注:windows的代码在编译过程中可能会出现InternetGetConnectedState找不到定义的情况,时因为gcc编译时链接不到Wininet的库,解决的方法是在Makefile文件中添加库的链接 -lwininet.